21087943 has 2 divisors, whose sum is σ = 21087944. Its totient is φ = 21087942.

The previous prime is 21087919. The next prime is 21087949. The reversal of 21087943 is 34978012.

21087943 is nontrivially palindromic in base 12.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21087943 - 2⁹ = 21087431 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21087899 and 21087908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21087949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10543971 + 10543972.

It is an arithmetic number, because the mean of its divisors is an integer number (10543972).

Almost surely, 2^21087943 is an apocalyptic number.

21087943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21087943 is an equidigital number, since it uses as much as digits as its factorization.

21087943 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 21087943 is about 4592.1610381170. The cubic root of 21087943 is about 276.2770052018.

The spelling of 21087943 in words is "twenty-one million, eighty-seven thousand, nine hundred forty-three".